Skeletal muscle is the largest storage reservoir for glucose in the body, and defects in insulin action to promote muscle glucose uptake can result in elevations of circulating glucose concentrations and altered muscle glycogen concentrations. Despite the importance of understanding the molecular mechanisms of insulin action in skeletal muscle, primarily for technical reasons, there has been relatively little focus on this tissue. RNA interference (RNAi) technology for knocking-down the expression of specific genes is a powerful tool to study gene function, but its recent application to mammals is still largely restricted to cell models due to limitations in gene delivery systems. Our recent studies demonstrate that electroporation is a reliable method for efficient transfection of skeletal muscle in vivo, and thus opens the way for implementing the RNAi technology in skeletal muscle. However, for this technique to be adapted to skeletal muscle we will need to make significant adjustments to the methodology. The specific aims for this pilot and feasibility project are: #1) To develop a method to use RNAi gene silencing for studies of adult skeletal muscle in vivo; #2) To determine if the RNAi gene silencing approach can be used to disrupt glucose transport and insulin action in skeletal muscle in vivo; and #3) To use the RNAi gene silencing approach to ameliorate skeletal muscle insulin resistance. The successful implementation of RNAi methodology in skeletal muscle will provide an extremely valuable tool to study the molecular mechanisms regulating muscle metabolism and function in vivo, as well as for elucidating specific mechanisms underlying skeletal muscle insulin resistance. Ultimately, this approach could provide the basis for treatment of skeletal muscle insulin resistance and other chronic muscle diseases such as the dystrophies.